A moving mirror can be used in a Michelson interferometer for Fourier transform infrared spectroscopy. Moving-mirror interferometers include a beamsplitter for dividing a beam of entrant radiation into two beams. The beams are reunited at the same beamsplitter, after redirection by reflecting elements, one or more of which elements is moved to change the relative path lengths for the two beams within the interferometer. A retroreflector can be mounted to a motor in the Michelson interferometer that enables translational movement of the retroreflecting means, such as a linear flexure motor.
The optical characteristics of the retroreflective surface are attributable to the surface figure of each mirror and mutually perpendicularity of reflective surfaces. The retroreflector's optical characteristic can be affected by gravity, thermal expansion or contraction, mechanical stress etc. Deformation in surface quality of around tens of nanometer or mutual perpendicularity of the order of arc seconds may result in the loss of efficiency in the interferometer.
The disadvantageous effects are generally exacerbated, moreover, when the interferometer is employed in an industrial setting. The interferometer can be difficult to assemble and align after replacement or repair of their components.